Products containing any active ingredients other than 'DXM' or 'Dextromethorphan' should not be used.

High doses of Guaifenesin can cause severe nausea and vomiting.

High doses of Acetaminophen can cause liver-damage and may be fatal. Some brands of DXM containing cough-syrups, including Drixoral Cough and Fever contain acetaminophen.

High doses of Chlorpheniramine Maleate can cause severe and life-threatening symptoms including seizures, loss of consciousness, bleeding from skin, mouth, rectum, and vagina, and possibly death. Some brands, including Coricidin Cough and Cold contain Chlorpheniramine maleate.

Do not take DXM if you are using, or have used an MAO Inhibitor within the last 2 weeks.

MAOI's include harmine & harmaline, as well as many anti-depressants.

Check with a doctor if you're unsure whether you medication contains MAOI's.

When combined with MAOI's, DXM can cause "serotonin syndrome" with fever, hypertension, and arrhythmias.

Do not take DXM if you are using, or have used an SSRIs within the last 2 weeks.

Nausea, stomach cramps, and other unpleasant gastro-intestinal effects are common and may persist for days after use.

Itching and other skin reactions have been reported.

The large amount of glucose, thickeners, etc., present in many cough syrups may be hard on your kidneys and pancreas.

Regular or frequent DXM use can lead to craving the experience and to emotional dependence. Although not common, some people go on to use DXM daily and can find it difficult to quit.

It is not yet established whether regular use of DXM causes physical dependence (physical withdrawal symptoms upon stopping regular use). Some users report a 1-2 week "hangover" period after stopping use which could suggest mild physical withdrawal. There is no evidence of life-threatening health risks from withdrawal, but there is little data available on the subject.

Regular users experience tolerance and require increased dosages to achieve the same level of effects.

Olney's Lesions: The theory that DXM may cause this type of brain lesioning is based on extrapolation from other NMDA antagonist actions and is not considered definitive.